* {
    margin: 0;
    padding: 0;
}
.all {
    width: 100%;
    height: 100%;
    position: fixed;
    background-repeat: no-repeat;
    background-size: 100% 100%;
    background-image: url(../resource/壁纸.jpg);
}
.bg {
    width: 100%;
    height: 600px;
    display: flex;
    justify-content: center;
    align-items: center;
}
@mixin alert_one {
    position: absolute;
    width: 360px;
    height: 80px;
}
.login_div {
    width: 400px;
    height: 400px;
    top: 100px;
    background-color: grey;
    border-radius: 5%;
}
.po_re {
    position: relative;
    left: 20px;
    width: 360px;
    height: 350px;
    background-color: black;
}
.title {
    @include alert_one;
    background-color:red;
    z-index: 2;
} 
.center {
    @include alert_one;
    height: 150px;
    top: 80px;
    background-color: pink;
}
.bottom {
    @include alert_one;
    top: 380px;
    background-color: green;
}
.title_font {
    width: 200px;
    height: 50px;
    margin-left: 80px;
    text-align: center;
    font-size: 18px;
    line-height: 50px;
    background-color: pink;
}